1. Field of the Invention
The present invention relates to a system for varying the volume and pressure of a coolant produced within machining and cutting tools and, more specifically, to a control system that regulates the speed of a coolant pump based on sensed coolant pressure, and the size of a coolant delivery orifice.
2. Description of the Related Art
Many types of cutting tools require that coolant (and/or lubricant) be delivered directly to the surface being cut. These fluid cooled tools include but are not limited to: drill presses; end mills; routers; and milling cutters. In prior art devices pressurized coolant is supplied by a single speed pump, and pressure control (required due to varying coolant flow requirements during machine processes) is accomplished using pressure relief valves and/or excess coolant is simply allowed to flow through the tool, filter and return lines. These pressure control methods result in reduced filter and pump life, increased heat and foam, and higher energy costs. By controlling the pump motor speed, the present invention overcomes these drawbacks. U.S. Pat. No. 5,028,176, issued on Jul. 2, 1991 to Delventhal et al., discloses a glass drilling machine having a pressure transducer for monitoring cooling fluid back pressure and a regulator for controlling the position of a drill bit based on this back pressure. U.S. Pat. No. 5,559,713 issued on Sep. 24, 1996 to Brown et al., discloses a chip buildup detection and control system, including a computer, for monitoring coolant flow to the cutter of a machine tool and controlling the machining operation and coolant flow. A flow transducer is used to control coolant flow from a high pressure pump. U.S. Pat. No. 5,601,414, issued on Feb. 11, 1997 to DiRe, discloses a programmable logic controller that monitors a fluid pressure and controls a pump motor to regulate pressure within the pump, under abnormal fluctuations. The use of this device to control coolant flow, is not disclosed. British Patent Application No. 2,010,137 (Martin), published on Jun. 27, 1979, discloses a machine tool coolant distribution system that delivers coolant only to those tools in the working position. Control of the pump motor speed is not discussed.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a programmable, variable volume and pressure, coolant system solving the aforementioned problems is desired.